Back from a few days away with a little more experience getting through airports.

On the way there I wore a vecro-fastened kilt, no belt, and I removed the sporran before walking through the scanner, no problems.

On the return trip I wore a USAK trad. PV with metal buckles.
I took off the Xmarks pin, belt and sporran.

I asked the officer at the scanner if my buckles would be a problem and said I really didn't want to take the kilt off

I went through with no problems and was told that if I got through this scanner I would get through any in the world since it was among the most sensitive.

So, it is now confirmed, buckles are no problem.